Limited access to dental care exacerbates oral health care disparities in underserved populations. The barriers in access at the individual level have been explored to a large extent;however, the impact of the dental care system on access is poorly understood. Reduced access has been linked to a lower overall supply of dentists, but little is known about the relationship between the specific characteristics of dental providers, such as education and practice setting, and access. The specific aims of this project are: 1) to assess the impact of dentist characteristics on access to dental care of underserved populations;and 2) to assess the potential differences in impact of dentist characteristics on specific categories of the underserved, such as children, low- income, and racial/ethnic populations. Using Andersen's conceptual framework of access to care, it is hypothesized that access to dental care is influenced by the context in which dental care is delivered, or the dental care system, in addition to individual characteristics. Measures of the dental care system are primarily conceptualized as personal and practice characteristics of dentists in the medical study service area where individuals reside. The data for this study include an existing population-based survey of individuals, an existing representative survey of dentists in private practice, and existing administrative data. The dependent variables (length of time since last dental visit and unmet dental care) and individual level independent variables will be obtained from the population survey. Independent variables measuring personal and practice characteristics of dentists will be obtained from the dentist survey. Examples of the latter measures are percentages of private practice dentists in the medical study service area who accept discounted fees, participate in public insurance programs, or have large practices (as indicated by number of various personnel and multiple practice locations). Additional independent variables on supply or availability of other dental care providers will be obtained from administrative data (e.g. designation of dental health professional shortage area, number of visits to community-based clinics). The impact of dentist characteristics on access will be examined in multinomial and dichotomous logistic regression models, controlling for individual and other predictors of access to dental care. Both models will be stratified by subgroups of underserved populations to assess potential differences in predictors of access among groups. Improving access to dental care is the solution most likely to reduce observed disparities in oral health of underserved populations. Research that identifies systemic barriers in access to care of the underserved populations is needed to inform policies designed to diminish oral health disparities. Project Narrative: Relevance Statement Improving access to dental care is the solution most likely to reduce observed disparities in oral health of underserved populations. Research that identifies systemic barriers in access to care of the underserved populations is needed to inform policies designed to diminish oral health disparities.